Remove all deprecated API usage from bindings/v8/custom

R=haraken@chromium.org, jochen@chromium.org, mkwst@chromium.org
BUG=324225

Review URL: https://codereview.chromium.org/94993005

git-svn-id: svn://svn.chromium.org/blink/trunk@162850 bbb929c8-8fbe-4397-9dbb-9b2b20218538